mineral

Ruby

Corundum (Al2O3 with Chromium traces)

Hardness: 9 on Mohs scale; Color: Pinkish-red to pigeon-blood red; Luster: Vitreous to sub-adamantine; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (parting may be present); Specific Gravity: 3.97-4.05.

Hardness: 9 on Mohs scale
Color: Pinkish-red to pigeon-blood red
Luster: Vitreous to sub-adamantine

Identified June 6, 2026More mineral →

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Physical properties

Formation & geological history

Formed in metamorphic rocks such as marble or schist, and in igneous rocks like basalt. Rubies are created under high pressure and intense heat deep within the Earth's crust, often in limestone or chromium-rich environments.

Uses & applications

Primarily used as a precious gemstone in jewelry (rings, earrings, necklaces). Also used in industrial applications like ruby lasers, watch bearings, and specialized scientific instruments due to its extreme hardness.

Geological facts

The red color is caused specifically by the presence of chromium. It is one of the four traditional 'precious' stones alongside diamond, sapphire, and emerald. Highly fluorescent under UV light, enhancing its glow.

Field identification & locations

Identified by its distinctive red color, extreme hardness (only diamonds are harder), and heavy specific gravity. Commonly found in Myanmar (Burma), Madagascar, Thailand, and Mozambique. Check for 'silk' inclusions to distinguish natural from synthetic stones.